The invention relates to a conveyor mat built up of first and second modules, made in one piece of synthetic material, the width of the first modules being substantially twice the width of the second modules, with the modules, viewed in the longitudinal direction of the mat, being staggered, each module consisting of a plurality of substantially equally spaced-apart hinge plates, each extending over substantially the entire length of the module and each having hinge loops at the two ends thereof, the hinge plates of a module being coupled by means of at least one transverse rib disposed between the two ends of those hinge plates, the ends of the hinge plates being disposed at a longitudinal side of a module between the ends of the hinge plates of an adjacent module in the longitudinal direction of the mat, the hinge loops of the two modules being substantially in alignment and coupled to each other by means of a hinge pin extending through the hinge loops, there being provided means for locking the hinge pin relatively to the modules.
Such a conveyor mat, built up of modules, is disclosed in U.S. Pat. No. 3,870,141 and is for instance used in the packaging industry, in bottling plants and the like, wherein the mat may have a relatively large width, up to some meters, and be designed as an endless conveyor mat, which at the beginning and the end of a conveying path is guided over sprocket wheels arranged across the width of the conveyor.
In practice, it is often desired that separate conveyor mats can run side by side so as to form a conveying surface. The juxtaposed mats may have the same speed, but may also have different speeds. To ensure a trouble-free conveyance in such a case, the transition from one mat to an adjacent mat should exhibit as few interruptions of the conveyor surface as possible, and the lateral side of each of the mats should be as flat as possible to enable longitudinal movement of the mats relative to each other. The known mat does not meet this requirement, because the hinge pins by which the modules are coupled to each other have a head projecting from the lateral side of the mat, so that in the case of juxtaposed mats, the heads of the hinge pins of adjacent mats may get caught one behind the other, while the conveying surface formed by adjoining mats also exhibits undesired irregularities.
It is observed that European Patent Document 0288409 discloses a conveyor mat which modules are staggered relative to each other and wherein the end hinge plates of the modules disposed at the lateral sides of the mat are designed such that they lie in one line with each other, in order that the mat has a flat lateral side. The hinge pins are locked by means of a cap-shaped locking member axially disposed in the hinge pin opening of each end hinge plate, which locking member is fixed by clicking it by a thickened end thereof behind the inwardly directed side of the end hinge plate. Such caps have the drawback that they cannot readily be removed and easily come loose under the influence of forces exerted through the hinge pins in axial direction. Moreover, a cap only locks one hinge pin and not, as in the invention, two hinge pins at the same time. However, the major drawback of this known conveyor mat is that it is built up of five different types of modules. Using five different types of modules for one type of mat renders the assembly of the mat troublesome and labor-intensive, with a substantial chance of mistakes, and is costly because five different types of modules should be held in store.
It is further observed that U.S. Pat. No. 4,893,710 discloses a conveyor mat of the "raised rib" type wherein a hinge pin is locked by a plate-shaped locking member which can be inserted into a slot-shaped opening formed in the last hinge plate of a module disposed at the lateral side of the mat, the side face of the plate-shaped part being provided with a cam-shaped thickening which engages the hole of the hinge pin by means of a click connection. This known mat has as a drawback that each module disposed at the lateral side of the mat comprises a locking member for a hinge pin, so that the hole must be built up of five different modules, which renders the composition of a mat laborious with much chance of mistakes. A further drawback is that at the location of the plate-shaped locking means the conveying surface is interrupted and that the conveyor mat has no flat lateral side, because the portion of the end hinge plate of a module disposed at the lateral side of the mat, in which portion the locking elements have been provided projects laterally from the rest of that hinge plate.